The present invention relates to a method for controlling a hybrid drive system based solely on managing the level of charge of the battery. A hybrid drive system of a vehicle, in particular of a motor vehicle, is generally defined as a set of members that equip the hybrid vehicle, comprising in particular:                a heat engine intended to supply the main drive energy;        an electric machine (ELM) coupled to the drive wheels of the vehicle using a fixed or variable gear reduction ratio and adapted to operate in motor or generator mode: in motor mode, the machine supplies electric energy to the drive wheels, and in generator mode, the electric machine transforms the mechanical energy supplied by the heat engine and/or the wheels (regenerative braking) into electrical energy stored in a battery; “battery” is more generally defined as a system for storing electrical energy, which can take the form of one or more accumulator-based elements and/or super capacitors, also known as super condensers, used alone or in combination;        an electric machine that makes it possible to start the heat engine, e.g., in a “Stop-and-Go” operating mode;        an active regenerative braking system, i.e., controlled by the brake pedal, for example, or a passive one, i.e., controlled by the beginning of the accelerator movement, for example.        
The need to reduce global warming by reducing CO2 emissions has accelerated the development of hybrid drive systems.
In order to optimize the efficiency of such a drive system comprising multiple members, one must have a control system to supervise the energy sources used in the drive system by controlling the various members of the drive system each in turn or at the same time.
Of the various possible operating modes of a hybrid drive system, we will distinguish primarily the following:                pure electric drive;        pure combustion drive,        combined combustion and electric drive (boost function);        combustion drive and battery recharge;        pure electric braking;        pure dissipative braking;        electric and dissipative braking        
Various strategies exist for controlling a hybrid vehicle, which are generally based on heat engine and electric motor outputs, as well as the outputs of the battery and the associated power electronics. From document US-B2-7173396, a control process is also known that uses battery control in a hybrid drive system, which determines battery discharge and recharge according to the various operating conditions of the hybrid vehicle.